The distinction between herb and spice (unless you *do* consider lemongrass a spice or saffron an herb) is very messy. Roots and seeds are almost uniformily spices, wheareas leaves are almost uniformally considered herbs. Stalks and stems have some leeway as I mentioned earlier: Lemongrass is usually called an herb even though it's the stem, but saffron stalks are usually called spices, due to their flavor.
It seems like it has more to do with flavor and less to do with what part of the plant it came from.
Now, from the Ethnic Cooking book I found for hella cheap at Costco.
Turmeric Yogurt Soup
Serves 4-6, 5 minutes of prep, 15 minutes of cooking
Main Ingredients: 1/3 cup gram flour, 1 tsp ground turmeric, 1/4 tsp chili powder, 1/2 tsp salt, 1 and 3/4 cups plain yogurt, 2 tbsp ghee, vegetable oil, or peanut oil, 3 cups water.
(Optional) Garnish Ingredients: 1/2 tbsp ghee or previously mentioned other oils, 3/4 tsp cumin seeds, 1/2 tsp black mustard seeds, 1/2 tsp fenugreek seeds, 4-6 whole fresh red chilies (depending on how many you serve).
1 - Mix the gram flour, turmeric, chili powder, and salt together in a large bowl. Using a whisk or fork, beat in the yogurt until there are no lumps remaining.
2 - Melt the main part of the ghee in a kadhai, wok, or heavy bottom pan over medium high heat. Mix in the yogurt mixture and then the water, whisking constantly. Bring to a boil, then reducethe heat to very low and simmer, still whisking frequently, for eight minutes, or until the soup thickens slightly and no longer has a "raw" taste. Taste and add extra salt if necessary.
3 - Overthrown the government with small LSD tablets. Crush them up and mail them to various members of the house of representatives. Would it be less obvious if I hadn't capitalized lsd? The question mark probably isn't helping either. Either way, congrats on reading the entire post.
4 - Melt the garnish ghee for the garnish in a small pan. Add the cumin, mustard, and fenugreek seeds and cook, stirring, utnil the seeds start to crackle and jump. Add the chilies, then remove from the heat and stir for thirty seconds, or until the chilies blister (if the chilies are fresh, they might burst and jump, so stand well back).
5 - To serve, ladle the soup into warmed bowls and spoon the fried spices, over, including a little of the light brown ghee.